def frombuffer(space, w_buffer, w_dtype=None, count=-1, offset=0):
dtype = space.interp_w(
descriptor.W_Dtype,
space.call_function(space.gettypefor(descriptor.W_Dtype), w_dtype))
if dtype.elsize == 0:
raise oefmt(space.w_ValueError, "itemsize cannot be zero in type")
try:
buf = _getbuffer(space, w_buffer)
except OperationError as e:
if not e.match(space, space.w_TypeError):
raise
w_buffer = space.call_method(w_buffer, '__buffer__',
space.newint(space.BUF_FULL_RO))
buf = _getbuffer(space, w_buffer)
ts = buf.getlength()
if offset < 0 or offset > ts:
raise oefmt(
space.w_ValueError,
"offset must be non-negative and no greater than "
"buffer length (%d)", ts)
s = ts - offset
if offset:
buf = SubBuffer(buf, offset, s)
n = count
itemsize = dtype.elsize
assert itemsize > 0
if n < 0:
if s % itemsize != 0:
raise oefmt(space.w_ValueError,
"buffer size must be a multiple of element size")
n = s / itemsize
else:
if s < n * itemsize:
raise oefmt(space.w_ValueError,
"buffer is smaller than requested size")
try:
storage = buf.get_raw_address()
except ValueError:
a = W_NDimArray.from_shape(space, [n], dtype=dtype)
loop.fromstring_loop(space, a, dtype, itemsize, buf.as_str())
return a
else:
writable = not buf.readonly
return W_NDimArray.from_shape_and_storage(space, [n],
storage,
storage_bytes=s,
dtype=dtype,
w_base=w_buffer,
writable=writable)
def test_as_str_and_offset_maybe():
buf = StringBuffer('hello world')
assert buf.as_str_and_offset_maybe() == ('hello world', 0)
#
sbuf = SubBuffer(buf, 6, 5)
assert sbuf.getslice(0, 5, 1, 5) == 'world'
assert sbuf.as_str_and_offset_maybe() == ('hello world', 6)
#
ssbuf = SubBuffer(sbuf, 3, 2)
assert ssbuf.getslice(0, 2, 1, 2) == 'ld'
assert ssbuf.as_str_and_offset_maybe() == ('hello world', 9)
#
ss2buf = SubBuffer(sbuf, 1, -1)
assert ss2buf.as_str() == 'orld'
assert ss2buf.getlength() == 4
ss3buf = SubBuffer(ss2buf, 1, -1)
assert ss3buf.as_str() == 'rld'
assert ss3buf.getlength() == 3
#
ss4buf = SubBuffer(buf, 3, 4)
assert ss4buf.as_str() == 'lo w'
ss5buf = SubBuffer(ss4buf, 1, -1)
assert ss5buf.as_str() == 'o w'
assert ss5buf.getlength() == 3
def frombuffer(space, w_buffer, w_dtype=None, count=-1, offset=0):
dtype = space.interp_w(descriptor.W_Dtype,
space.call_function(space.gettypefor(descriptor.W_Dtype), w_dtype))
if dtype.elsize == 0:
raise oefmt(space.w_ValueError, "itemsize cannot be zero in type")
try:
buf = _getbuffer(space, w_buffer)
except OperationError as e:
if not e.match(space, space.w_TypeError):
raise
w_buffer = space.call_method(w_buffer, '__buffer__',
space.newint(space.BUF_FULL_RO))
buf = _getbuffer(space, w_buffer)
ts = buf.getlength()
if offset < 0 or offset > ts:
raise oefmt(space.w_ValueError,
"offset must be non-negative and no greater than "
"buffer length (%d)", ts)
s = ts - offset
if offset:
buf = SubBuffer(buf, offset, s)
n = count
itemsize = dtype.elsize
assert itemsize > 0
if n < 0:
if s % itemsize != 0:
raise oefmt(space.w_ValueError,
"buffer size must be a multiple of element size")
n = s / itemsize
else:
if s < n * itemsize:
raise oefmt(space.w_ValueError,
"buffer is smaller than requested size")
try:
storage = buf.get_raw_address()
except ValueError:
a = W_NDimArray.from_shape(space, [n], dtype=dtype)
loop.fromstring_loop(space, a, dtype, itemsize, buf.as_str())
return a
else:
writable = not buf.readonly
return W_NDimArray.from_shape_and_storage(space, [n], storage, storage_bytes=s,
dtype=dtype, w_base=w_buffer, writable=writable)
